System of motor control.



PATENTBD APR. 30, 190 7.

W. L. MERRILL. SYSTEM OF MOTOR CONTROL.

APPLICATION FILED JULY 21, 1906.

SHEETS-SHEET l.

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Atty.

l V/Zbur L. Mar/"XL L W/l nesse's; a! w W. L. MERRILL.

SYSTEM OF MOTOR CONTROL. APPLICATION FILED JULY 21, 1906.

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Witnesses;

PATENTED APR. 30, 1907.

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Atty.

No. 851.823. PATENTED APR. 80, 1907. W. L. MERRILL. SYSTEM OF MOTOR CONTROL.

APPLICATION FILEI JULY 21, 1906.

4 SHEETS-SHEET 3.

\nVenkor Wilbur L. Mzrri l I,

PATBNTED APR. 30, 1907.

W. L. MERRILL. SYSTEM OF MOTOR CONTROL.

APPLIOATION FILED JULY 21, 1906.

4 SHEETS-SHISET 4.

7 m A MA... 5 v 1 INVENTUR.

UN lTEl) ST WILBUR L. MERRILL, OF

rn'rENr OEEIOE.

SOHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC C MPANY, A CORPORATION OF NEW YORK.

SYSTEM OF MOTOR CONTROL.

Specification of Letters Patent.

:atenteo April 30, 1907.

' Application filed July 21,1906. Serial No. 327,162.

to the control of electrically-operated bulkhead doors on board ship; though in some of its features not limited to this specific application. l

In the control of bulk-head doors on shipboard it is essential that each door be controllable both locally and from a distant oint, and such systems have been arranged heretofore with switching devices for each motor controllable both from a distance to connect the motor for lowering the door, and l manually by a man at the door to connect l the motor for either raising or lowering the '2 door. For convenience in the distant coni trol, the devices for actuating the switches by l the distant control have ordinarily been l grouped; the controlling devices for five or l six motors being connected in -a single cirl cult and controlled by a single switch at a distant point. The manual control has been so arranged that a man at any door can control the movement of that door, regardless of the condition of the control system, that is, whether the distant control-switch for the group to which that motor belongs is closed or not. It has further been the practice heretofore to arran e the switches for all the l motors so that eac motor is connected directly acrossthe power-mains when 0 eratingeither under distant or local contro One feature of my invention consists in so arranging the circuit connections and switching devices, that for the distant control all the motors of each group are connected in se- 1 ries with each other to the source. By means of my invention 1 am able greatly to reduce the size of wire required for the system, since the motors are connected in series instead of in parallel for the distant control, which is the only time they are likely to operate simultaneousl A single electromagnet su'll'lces for the distant control for the entire group of motors, instead of one or more magnets for each motor, as have been required heretofore, and the number of conductors extending to the emergency station is reduced. Furthermore, when all the doors of a group are closed, they are held firmly on their seats, so long as the circuit remains closed at the emergency station, with a ressure corresponding to the full torque oi the operating motor, andwithotrt any more current than is required to Operate one motor.

My invention further comprises an arrangement for determining the order of closing of the doors in each group.

My invention further comprises certain novel arrangements of the indicating devices for showing the operator at the emergency station the condition of all the doors.

My invention further comprises certain features in the construction and arran ement of the control switches and indicating devices at the emergency station.

In the accompanying drawings, Figure 1 5 re resents one of a system of bulk-head doors a( apted for control in accordance with my invention; Fig. 2 shows diagrammatically a motor control system arranged in accordance with my invention; Fig. 3 shows a development on a plane surface of the contacts of one of the switches in Fig. 2; Figs. 4, 5 and 6 show diagrammatically the circuit connections established by the switch of Fig. 3, in its three positions; Fig. 7 shows diagrammatically the circuit connections of the distant control and indicating devices; Fig. 8 shows an end elevation artly in cross-scotion of the motor-controlling switch shown diagrammatically in Fig. 3; Fig. 9 shows a side elevation of the same partly in cross section; and Figs. 10 and 11 show two crosssectional views-of the apparatus at the emergency station, the cross-section of Fig. 10 being taken on the line 10 1O of Fig. 11, and the cross-section of Fig. 11 being taken on the line 11-11 of Fig. 10.

In Fig. 1, A represents a bulkhead door vertically movable in the guides B, and carrying a rack a enga ing a pinion c on a shaft (1, which is driven y an electric motor D. E represents a controller for the electric mo; tor with handles on both sides of the bulkhead- J,

The circuit arrangements are shown in Fig. 2. In this figureD to D represent five motors which form one group for the distant control. In practice a sufficient number of closes its door, so that the motoris brought motors are connected in series in a group to to rest, the counter-electromotive force of the give the proper ohmic resistance to the motor circuit, when all the motors are at rest, j motor disappears so for drawing from the supply mains the deincreased to an amount limited only by the sired amount of current for starting. I find ohmic resistance of the motors, unless inthat nine or ten motors in a group give satisother motor has already started. Thus, if factory results for operatin sliding bulkthe friction of the several doors is unequal, head doors, but for different rinds of service I the doors will close successively; the doors this number should be raised. If there are with the smallest friction being closed first.

to not enough motors for a group to give the On the'other hand, if the friction of all the desired ohmic resistance, a dead resistance doors were exactly equal, all the doors would may obviously be inserted in series with the start simultaneously, but with reduced motors to bring the starting current down to speed. If any door shouldstick while movthe desired amount. E, E etc., represent I ing toward closed position, its motor would i 5 manually-operated reversing switches for the I be stopped, increasing the voltage on the terseveral motors, which are normally held in minals of the other motors and accelerating off position by the centering springs e. All their closing. As soon as the other doors are these reversing switches are identical, and closed, the current will again rise to a value one of them is shown in Fig. 3 with the con- 1 limited only by the ohmic resistance of the tacts developed on a plane surface. f re remotors, so that the maximum current is sup-' sents a switch contact controlled by an e ecl plied to the inotor driving the door which has tromagnet F, which, in turn, is controlled by I stuck. The doors will thus all be closed a control-switch G at the distant point or either serially or simultaneously, according emergency station. H and H represent the i to their relative friction. .l' have found by power-mains, from which three branches h actual test that the time consumed in closing It and b are carriedoff to the motors of this all the doors of the group is substantially the group. 1 (shown in'Fig. 3), J and K represame whether the motors all start simultanesent resistances. ously or whether one door closes before anlVith the reversing switches all in off posiother starts.

0 tion, where they are' normally held when not If it is desired to close the doors in a preoperated by a man at the door, the motors determined order, the adjustable resistances are all connected in series in the line-wire h. K may be employed to shunt the motors, and This will be seen by tracing out the circuits by properly adjusting these resistances, the of the controller E in Fig. 3 through the conoors may be caused to close in any desired 3 5 tacts which are closed when. this switch is in order. It is sometimes desirable in an emeroff position. These circuit connections are geney that the outer doors nearest the hull of shown in dotted lines in'Fig. 4. The linethe ship should be closed.first,and this result wires h and b consequently form a series may be obtained by means of the resistance circuit, including. all the motors in series. shown. In Fig. 2 these resistances are so 40 T e line-Wire k is connected to the power adjusted that the door operated by motor I) main H and the line-wire h is arranged to will close first, followed by D etc, in order. be connected to the power-main H when the I While I have shown the resistances shunting normally open switch f is closed. Conseonly the fields of the motors, it is evident quently, when switch G is closed, energizing i that they maybe placed lIl shunt to both field 5 magnet F so as to close switch f, all five mol and armature, or to the armature alone. Fur tors are connected in series across the power- I thermore, it will be seen that the same result mains. may be obtained mechanically, as by adjust- Neglecting for a moment the resistances in the friction of the several oorsinagroup. it will be seen that if tlife'motors are all of T have thus far described only the (118- similar design, the torque of all the motors will tant control. The local control 1 s obtained be the same, since the same current is assmanually by moving the controlh switch ing through the field and armature of a l the from off position to either rais ng or o'wering motors. The amount of this current, when position. It will be seen by inspecting the the switch f is first closed, is determined simcontact arrangement of the switc E 1n F 1g.

ply by the ohmic resistance of'the five mo- 3 that moving the switch from its mid- 0S1- tors in series and by placing the proper numtlon to either of its other pos tions Wll cut her of motors in series may be made any- 1 the motor D out of the ser1es c1rcu1t,-a1 1d w ll thing desired. Since the torque of all the substitute the resistance I in that circuit.

. motors is the same, the motor or motors con- This-resistance is pro ortioned in amount to 6 nected to the doors having the least friction correspond to the 0 io resistance of. the will start up first. The counter-electromomotor D. Thus, the motor may be cut out tive force producedbyrotation in the first without interrupting the series circuit conmotor that starts tendsto reduce the curtaining the other motors, or interfering with rent-flow and to prevent the other motors thedistant control of the other motors. In

6 5 from starting; but as soon as the first motor its two operative positions the switch E con-,

that the current is again nects the motor D senses across the conductors h and h for opposite directions of rotation. This connection is made through the resistance J in order to limit the current-flow, since the motor is now connected directly across the power-mains instead of in series with the other four motors. The circuit connections established when. switch E is moved manually to raise and to lower the door are shown re spectively in Figs. and 6.

With the arrangement above described, it will be seen that the conductors hi, h and 7t carry the current of only asingle motor, unless two motors of the same group are being operated manually at the same time. Consequently these Wire's may be made much half the doors of the group are already smaller than is necessar it all five motors were connected para lel for the distant control, as in the ordinary arrangement. Furthermore, by the motors a single switch contact f suflices for the control of all the motors lrom distant point. It will furthermore be seen that the distant control is automatically selective, that is, if a portion of the doors of any group are ahead closed when the distant controlswitch is c osed, onl the motors of the doors which are open will have to operate,so that it closed, only half the usual time is required for closing the remaining doors.

{Figs 8 and 9 show a suitable construction.

for the motor controlling switch E, shown through Figs. 8 and 9;

duce a quick when released by diagrammatically in Fig. 3. As shown in the switch E comprises a' rotatable drum c and stationary contact-fingers e. The shaft 0* of the drum extends the casing of the switch, and is pro vided with an operating-handle a e repre sents a centering s ring for holding the switch normally in mic -position, except when moved by hand. The "switch is provided with a star-wheel e", on which rides a roller e carried by a pivoted member 6''. A spring (1 resses against this member, holding the m1 ere against the starewheel, so as to promovement of the switch from one positionto anotherwhen moved by hand, and also to stop the' switch in midosition hand and returne by the spring e I Fig. 7 shows the circuit connections of the apparatus at the ei'nergency station, includ ing the controlling switch and the indicating devices for showing whether the doors are open or closed. DD represent two groups of motors, one of which may be on the star board, and the other on the port side of the I full brilliancy.

ship. The controlling switches and the conductor it, shown in Fig. 2, are omitted from this figure for the sakeof sim licity. One I u of motors is controlled y a magnetcoil and the other by a magnet-coil F ed a pair of signal switches L and Ll, whi 'h are indicated diathe series arrangement of.

grammatically in Fig. 1, and whichlare normally open as long as the door stands in any mid-position. When the door is in its extremc upper position, the switch L is engaged by the door, and closed. Similarly, when the door is completely closed, the switch L is engaged thereby and closed.

represents the controlling switch at the emer gency station, which l have shown as comprising a pair of movable contacts 9 and. g, controlling the magnet-coils F and F respectively. Although I have shown only one magnet-coil controlled by each contact,

it is obvious that as many magnet-coils asdesired may be placed in series or in parallel with magnet-coils F or F, so as to control as many groups of doors as desired. by a single contact g. M represents a switch at the emergency station normally held open by the spring m, and controlling the cirouits'of the return signal devices N and N, which may consist of incandescent lamps, or any other suitable indicating means. The lamps N correspond to the doors controlled by the magnet-coil F, and the lamps N correspond to the doors controlled by the magnet-coil F Two lamps are provided for each door, and are connected in series. The contacts of l the switch M are arranged to connect each pair of lamps across the source of current indicated by the line-wires H and H A lead from the point of connection between the two lamps of each pair is carried to the signal switches L and L of the door corresponding to those lamps. These switches are arranged when closed to connect the oint between the twodamps to one or the other of the mains H and H If all the consequently all the switches in and l are o erator at the emergency station, each pair 0 lamps will be connected across the source, and since the normal voltage of each lamp is the same as the voltage of the mains, the lamps will burn at a brilliancy corresponding to half-voltage. This tellsthe operator that all the doors are in mid-position. it some of the doors are wide open, so that some erthe switches L are closed, the intermediate points between the lamps of the pairs corresponding to those doors will be connected through the switches L to thcpower-main H so that when the switch lower lamps of those pairs. will be short-circuited, and conse uently will be dark, while the upper lamps 0 those pairs will burn with In this way an indication is l iven that some of the doors are wide open. I n the other hand, if some of the doors are closed, some of the switches L will be closed, so that some of the up er lamps will be dark, and some of the lower lamps at full brilliancy. Consequently, by closing switch M, and observing the condition doors are in mid-position, and

M is closed the switch to determine its tions.

' electrical connections, circuits for the two bridging contacts cover 0 is the operator at the emergency station can always obtain complete information as to the condition of all the doors.

Figs. 10 and 11 show the arrangement of the controlling switch and indicating lamps at the emergency station. The indicating lamps are shown arranged for twenty-four doors which might be grouped in four equal groups of six doors each or in groups in which the number of motors in series differs to meet the requirements of dilferent'kinds of service. Since the apparatus is designed for use on shipboar ture, and formed The controlling switch G for the motor-controlling magnets is shown as comprising a m pivoted on the base 0 and carrying g and g controlling the motors on the starboard and port sides of the vessel, respectively. Contact fingers g mounted on a standard P on base 0 are arranged to be bridged by the movable contacts. The operating shaft 9 of the switch extends through the cover and is provided with a handle 9", which is removably secured to the shaft in any suitable Way. g represents a spring normally holding the switch in' open-circuitposition, and g represents a spring-actuated latch adapted to engage notches in a member 9 on the shaft of the consequently 1s inclosed in a casing N represents the indicating lamps, which are arranged in pairs, as described above, and which are carried by the cover 0. In order that the cover may be removed readily, without the necessity of unfastenin any amps are closed in the following manner; a conductor n connects one terminal of one lamp of each pair through a fuse n to the common conductor n, shown in Fig. 7 while a second conductor a connects one terminal of the other lamp of each pair through a fuse n to the common conductor n two terminals of the lamps of each pair are connected together, and a conductor a connects their points of connection to a support n? on the cover. All the conductors just mentioned are carried by the cover and are removable therewith. To connect these conductors to the leads to the external circuits a conductor n conductor n7.

1s provided, carried by in electrical contact with the This conductor a is in the form of a spring contact linger ada ted to press against the contact block a w ien the in position, as shown in Fig. 10. This contacts-block n" is secured to the base and to it are connected the leads a" from the external circuits. In this manner the lamp circuits are all disconnected and remade automatically,

and replaced. l

the support a it must be protected from moisby a base portion 0 and a cover 0 off and closed posi when the cover is removed more difficult than wit a source of current, and

The switch M controlling the lamp circuits comprises a movable member supported in the standard P on the base 0, and 1s arranged to move longitudinally in this standard. It is normally held in the raised position shown in Fig. 10 by a compression sprin m. The member M carries insulated bri ging contacts m, which, when member is moved downward, bridge stationary contact-fingers m carried by the standard P. For operating switch member M, a push-button m is provided in the cover 0 which, when depressed, is adapted to engage the end of member M- and-move it downward against The reason for emt ecover after it has been removed. If member M extended through the cover, this mem ber, together with the shaft 9 would make two members which would have to register with their respective openings in the cover in order that the cover might be replaced. This would make the replacip of the cover much i the construction shown, in which the shaft g is the only part attached to the base which projects through the cover and must be brought into registry with an o ening in the cover.

What claim as new and desire to secure by Letters Patent; of the United States, is:

1. In a control is stem, a plurality of motors, means controllable from a distance for connecting said motors in series to a source of current, and meansat each motor for connecting that motor to the source independently of the other motors.

2. In a motor-control system, a plurality of motors, electro ma netically actuated means for connecting sair motors in series to manually-o erated means at each motor for connecting t lat motor to the source independently of the other motors. I

3.In a motor-control system, a plurality of motors, a magnetically -actuated switch arranged to connect, said motors in series to a source of current for one direction of rotation, and a manually-operated switch for each motor ada ted to connect that motor to the source for either direction of rotation independently of the other motors.

4. In combination, a plurality of motors, a control system for connecting said motors in series to a source of current, a switch at a dis tant point controlling said control system, and manually-o )erated means at each motor for connecting that motor to the source independently of the other motors.

5. In a motor-control s 'stem, a plurality of motors, a series circuit including said motors in series with a source of current, means controllable from a distance for closing said series circuit, and means at each motor for of motors, a manually-operated reversing of motors, a series circuit including said mopcndently of the other motors.

access '3 magnet for closing said switch, a control switch at a distant point in circuit with said electromagnet, and means ateach motor for cutting the motor out of theseries circuit and connecting it to the source independently of the other motors;

13. In a motor-control system, a plurality of motors, a series circuit including said 1no-= tors in series and a source of current, a normally-open switch in said circuit, an electromagnet for closing said switch, a control switch at a distant point in circuit with said electromagnet, means at each motor for cutting the motor out of the series circuit and connecting it to the source independently of the other motors, and a resistance arrange .to be inserted in said series circuit when a motor is cut out.

14. in a motor-control system. a plurality of motors, a manuallyoperated reversing switch for each motor, means each switch normally in its oli position, contacts on each switch connected to the motor and arranged to no closed when the switch is in off osition, a circuit extending? through the said contacts of the severe. switches series, a normally open switch arranged when closed to connect said circuit to a source of current, an electromagnet for closin said normally-open switch, and a cont-rdl switch at a distant with said electromagnet.

15. in a motor-control system, a plurality of motors, a series circuit including said motors in series and a source of current, means controllable from a distance for closing said series circuit, and means at each motor for connecting that motor to the source independently of the other motors without interrupting the series circuit.

iii. in a motor-control system, a plurality of motors, a series circuit including said inotors in series and a source of current, a norconnecting that motor to the source inde- 6. In a motor-control system, a plurality of motors, a series circuit mcluding said motors in series-and a source of'current, means controllable from a distance for closing said series circuit, a switch for each motor arranged to connect that motor to the source independently of the other motors, and a resistance arranged to be inserted in the series circuit by said switch.

7. in a motor-control system, a plurality of motors. a series circuit including said motors in series and a source of current, means controllable from a distance for closing said circuit, a manually-operated switch for each motor arranged to cut that motor out of the series circuit and to connect it to the source l or either direction of rotation independently of the other motors, and a resistance arranged to he insert-ed in the series circuit when a motor is cut aut.

8. in a motor-control system, a plurality of -motors, a manually operated reversing switch for each motor, means for holding each switch normally in its ofl position, contacts on cachswitch connected to the motor and arranged to he'closed when the switch is in offp\ sition, a circuit extending through the said contacts of the several switches in series, and means controllable from a distance for connecting said circuit to a source of current.

9. In a il'lOtOTcCOIllZTOl system, a plurality switch for each motor, means for holding each switch normally in its oil position, contacts oneach switch connected to the motor and arranged to be closed when the switch is in off position, a circuit extending through the said contacts of the several switches in series, means controllable from a distance for connecting said circuit to a source of current, and a resistance arranged to he inserted in said circuit-when one of said switches is moved from its oii position.

magnet for closing 10. In a motorcontrol system, a plurality said switch, a control switch at a. distant point in circuit with said electromagnet, and means at each motor "for cutting the motor out of the series circuit and connecting it to the source indenendently oi the othe motors.

l7 In a motor-control system, a plurality of motors, means controllable from a distance for connecting the motors in series to a source of current, and means at each motor for corniecting that motor to the source through a'resistance, independently of the other motors.

18. in a motor-control system, a plurality of motors, aseries circuit including said motors in series and a source of current, means controllable from a distance for closing sai series circuit, connecting that motor to the source'through a resistance independently of the other motors,

tors in series, and a source of current, means controllable from a distance for closing circuit, and means at each motor for cutting the motor out of circuit and substituting a resistance therefor. 11. In a motor-control system, a plurality of motors, a series circuit including said motors in series and a source of current, means controllable from a distance for closing said circuit, and means at each motor for cutting the motor out of circuit and substituting a resistance therefor and for connecting the motor to the source independently of the other motors.

12. In a motor-control system, a plurality of motors, a series circuit including said motors in series and a source of current, a normally-open switch in said circuit, an electro and means at each motor for for holding point in circuit really open switc'i in said circuit,,an electro:

19. In a motor-coidrol system, a plurality of motors, a series circuit including said motors in series anda source of current, means controllable from a distance for-closiiig'said through a resistance for either direction of rotation independently of the other motors.

:20. In a motor-control system, a plurality of motors, a series circuit including said motors in series and a source of current, means controllable from a distance for closing said circuit, and a manually-operated SVv'lLCil for each motor arranged to cut that motor out of the series circuit and to connect it to the source through a resistance for either direction of rotation independently of the other motors and without interrupting the series circuit.

21. In combination, a plurality of motors norn'zally connected in series, means for connecting the series circuit to a source of current, and a switch for each motor adapted to out said motor out of said circuit and to sub stitute a resistance therefor and to connect the motor to the source through a second resistance independently of the other motors.

22. In combination, a plurality of motors, means controllable from a distance for connecting-said motorsin series to a source of current, means for adjusting the relative torques of said motors, and means at each motor for connecting it to the source independently of the other motors;

23. In combination, a plurality of motors, means controllable from a distance for connecting said motors in series to a source of current, the circuits of said motors being adjusted for different torques in the several motors.

24. In combination, a plurality of motors, means controllable from a distance for connecting said motors in series to a source of current, adjustable resistances connected in shunt to 'the'several motors, and means at each motor for connecting it to the source independently of the other motors;

25. In combination, a plurality of motors, means controllable from a distance for conseries to a source of oursource indel l l l l l l i senses iat door to one or the urce accordmg as the devices of the pair for tl other terminal of the so door is fully opened or closed.

27. In a system of .control for bulk-head doors and the like, an emergency station, means controllable from the emergency slation for operating the doors, a pair of electroresponsive indicating devices at the emergency station for each door connected in series, a normally-open s\\ itch adapted to connect each pair of devices to a source of current, and switch contacts at each door arranged to connect the point of connection between the two devices of the pair [or that door to one-or the other =L0l11ll1litl of the source according as the door is fully opened or closed.

28. In a system of control-for bul doors and the like, an emergency station, means controllable from the emergency sia tion for operating the doors, a pair ol electroresrmnsive indicating devices at the emergency stationfor each door connected in series, connections from the outer terminals of each pair of devices to the terminals of a source of current, snitch contacts at the emergency station in said connecti ms,connections from the point of connection between the two devices of each pair to both terminals of the source, and switch contacts in the last-mentioned connections controlled by the movement of the door corresponding to that pair ol devices.

V In a system of control for bulk-head doors and the like, an emergency station, means controllable from the emergency slation for operating the doors, a pair of electro-responsive indicatin devices at the emergency station for each door connected in series, connections from the outer ler minals of each pair of devices to the terminals of a source of current, connections from the point of connection between the two devices of each pair to both terminals of the source, and switch contacts in the last-mentioned connections controlled the movement of the door corresponding that pair of devices.

30. In a system of control for bulk-head doors and the like, a controlling switch, a casing therefor comprising a base and a cover, electro-responsive indicating devices carried by the cover, terminal contacts se cured to the base, and contacts carried by the cover and connected to said devices adapted toengage the base eontactslwhen the cover is in position.

31. In a system of control for bulk-head doors and the like, a casing comprising a base and .a cover, 'a controlling switch mounted on said base within the casing, an operating shaft therefor extending through the cover, a removable handle on said shaft, electro responsive indicating devices carried by the cover, terminal contacts secured to k-llcad when said cover is inplace.

the base, and contacts carried by the cover and connected to said devices adapted to engage the base contacts when the cover is in position.

32. In combination, a casing com rising a base and a cover, a switch mounte on sai l base within said casing, an operating shaft therefor extending throu h said cover, a removable handle on said siaft, a spring-actuated reciprocating switch mounted on said base Within the casing, and a push-button carried by said cover and adapted when dopressed to engage sai reciprocating switc 33. Inoombinaion, a casing com rising a base and a cover, a switch mounte on said base Within said casing, an o erating shaft therefor extending through said cover, a removable handle on said shaft, a springactuated reciprocating member mounted on said base within said casing, a plurality of bridgin contacts carried by said member, a plura ity of sets of stationary contacts mounted on said base and adapted to be brid ed. by said bridging contacts, and a pushfill/L011 carried by said cover and adapted when deoressed to engage said reciprocating mem- )er when said cover is in place.

rality of doors,

of current and a plur out of said 34. in a hulk-head door system, a pin rality of doors, an electric motor for operating each door, means controllable from a distones for connecting a plurality of said motors in series to a source of current, and means at each door for connecting the operatin motor for that door to the source in epen ently of the other motors.

35. In a hulk-head door system, a plurality of doors, an electric motor for operating each door, a control system for connecting a plurality of said motors in series to a source of current, a switch at a distant point controlling said control system, and a marin ally-operated switch at each door for connecting the o erating motor for that door to the source in e 'endently of the other motors.

3-6. In a hullr-head door system, plurality of doors, an electric motor for operl ating each door, a circuit including a plurality i of said motors in series, means controllable from a distance for connecting said circuit to a source of current, and means at each 1 door for connecting the operatin motor for that door to the sourceindepen ently of l the other motors.

- 37. In a bulk-head door system, a pluan electric motor for operata circuit including a source ing each door,

ality of said motors in I series, a normally-open switch in said circuit, an electromsgnet controlling said switch, a switch at a distant point d at each door 'ior cutting the operating motor for that door circuit andlconnecting it to the i source independently of the other motors. l

controlling sai electromagnet, and means l each door'for connecting the o 38. In a bulk-head door systeni,-a plurality of doors, anelectric motor for operating each door, a circuit including a plu rality of said motors in series, means controllahle from a distance for connecting said circuit to a source ofcurrent, andmeans at crating motor for that door to the source in ependently of the other motors without interrupting said circuit.

39. in a bulk-head door ity of doors, an electric motor for operating each door, a circuit including a source of current and a plurality of said motors in series, a normally-open switch in said circuit, an electromagnet controlling said switch, a switch at a distant point controlling said electromagnet, and means at each door for cutting the operating motor for that door out of said circuit and connecting it to'the source independently of the other motors without interrupting said circuit.

40. in a hulk-head door system, aplurah ity of groups of doors, an electric motor for operating each door, the motors for each group oi doors being connected in series, and means controllable from a distance for con-=- necting each series circuit to a source of current.

41. in a bulk-head door system, a plural ity of groups of doors, an electric motor for operating each door, the motors for each group or doors being; connected in ser1es, a normallyopen SWl'td in each series circuit, an electromagnet controlling each switch, and means at a distant point controlling said ele'otromagnets.

42. in a bulk-head system, a plurality of groups pr" doors, an electric motor for operatmg eacn door, the motors for each group 0 doors being connected in series, a normallyopen switch in each series circuit, an electromagnet controlling each switch, switch contacts at a distant point controlling said electrornaonets, and a manually-operated switch eac.. door for connect ng the operating motor for that door to the source independentl of the other motors.

es. in built-head door system, a plurali y of groups of doors, on electric motor for oper each door, the motors for each groupoi doorsheing connected in ser es, means controllable from a distance for con" necting each series circuit to a-source of ourrent, and means for adjusting the relative operation of the doors of a group to deterthe order iniwhich they are to close.

so. in a built-head door system, a plurality of groups of doors, operating door, the -motors for each group oi doors being-connected in series, a normaliympen switchin each series circuit, eleotromagnet controlling each switch, switch contacts at a distant pcintcontrol ling said electromagnet, and meanrrior ad system, a pluralas 1,82 F

47. In a bullchead door system, a plurality of doors, an electric motor for operating each door, means controllable from a distance for connecting a plurality of said motors in series to a source of current, and means for adjusting the relative operation of the doors to determine their order of closin l 48. In a bulk-head door system, a plurality of doors, an electric motor for operating justing the relative operation of the doors of a group to determine the order in which they are to close.

45. In a bulk-head system, a plurality of groups of doors, an electric motor for operatmg each door, the motors for each group of doors being connected in series, and means controllable from a distance for connecting each series circuit to a source of current, the doors of each group being adjusted to close in a predetermined order.

46' in a bulk-head door system, a plural ity of groups of doors, an electric motor for operating each door, the motors for each group of doors being connected in series, a normally-open switch in each series circuit, an electromagnet controlling said switch, and a switch at a distant point controlling said electromagnet, the doors of each group being adjusted to close in a predetermined order.

each door, and means controllable from a distance for connecting a plurality of said motors in series to a source of current, said doors being adjusted torclose in a predeter mined order.

In Witness whereof, I have hereunto set my hand-this 20th day of July, 1906.

WELBUR L. MER;

Witnesses BENJAMIN B. HULL, H LEN Onrortn. 

